1. Field of the Invention
The present invention relates to a controller for effecting fuel and ignition control for each cylinder of an internal combustion engine mounted in, for example, a motor vehicle, and more particularly to an ignition controller for an internal combustion engine for making variable the ignition energization time in conjunction with fluctuations in the engine speed of an internal combustion engine.
2. Description of the Related Art
In an internal combustion engine of such as a vehicle-use engine, it is generally necessary to optimally control fuel injection and ignition timing for a plurality of cylinders in correspondence with the operating conditions. A so-called fuel ignition timing controller is known which is capable of ascertaining a reference crank angle signal for each cylinder by making use of the crank angle signal of the internal combustion engine and is capable of effecting ignition control on the basis of this signal as disclosed in JP-A-1-227873.
However, in the method of making variable the ignition energization timing in a case where the engine speed is changing, a first reference position signal is generated at a predetermined crank angle position, a second reference position signal is generated at another crank angle position, and an engine rotation period is determined from the first and second reference position signals. In a case where that period has dropped below a predetermined value is started at the first reference position, and the energization is completed at the second reference position. For this reason, although it has been possible to overcome the shortage of energization time in changes of rotation, particularly in the direction in which the number of revolutions rises, the energization time is therefore set to be long. Thus, a waste in electric power conventionally occurred.
In addition, the ignition energization is effected by a timer based on the first reference position signal in dependence on the aforementioned period. For this reason, in a case where the change of the engine speed is not a slow change, but the engine has been accelerated sharply, when the time of a timer value obtained from the first reference position has arrived, a time delay from a desired ignition crank angle can possibly occur. In a worst case, the ignition energization time can become too short.
The timing of ignition, i.e., the timing for sparking and detonating fuel, is the point of time when energization is completed. For this reason, conventional apparatuses were able to secure the ignition energization time, but not able to change the ignition timing. In addition, during a change in rotation, particularly during acceleration, the ignition timing occurs at a delayed angle. As a result, a shortage in the torque of the engine occurs, possibly leading to the deterioration of the sense of acceleration. Further, in the case where a reference interval is wide as with the first and second reference position signals, a time lag occurred in coping with a sudden change.
The present invention has been devised to overcome the above-described conventional problems, and an object of the invention is to provide an ignition controller for an internal combustion engine which appropriately secures the energization time for ignition after the ignition timing is set to a desired timing at the time of a change in the rotation of the internal combustion engine.
The ignition controller for an internal combustion engine in accordance with the invention includes: a crank angle sensor for generating a plurality of crank angle signals periodically in correspondence with a rotational angle of a crankshaft of an internal combustion engine; a cam sensor for generating cylinder discrimination information of the internal combustion engine in correspondence with a rotational angle of a camshaft rotating in synchronism with the crankshaft; and a control unit for controlling the ignition energization of each cylinder of the internal combustion engine on the basis of the crank angle signals and the cylinder information, wherein the control unit has an engine-speed detecting unit for detecting a change in an engine speed of the internal combustion engine and an ignition correcting unit for correcting ignition energization time, an ignition energization start timing, and an ignition timing in correspondence a changed engine speed in a case where the change in the engine speed is equal to a greater than a predetermined level.
The ignition controller for an internal combustion engine in accordance with the invention includes: the engine-speed detecting unit for detecting a change in the engine speed of the internal combustion engine on the basis of an average period of a crank angle and the ignition correcting unit for computing an ignition energization start on the basis of a change in the crank angle average period to correct the ignition energization time in a case where the change in the engine speed has been detected.
The ignition correcting unit of the ignition controller for an internal combustion engine in accordance with the invention effects correction on the basis of an ensuing estimated crank angle average period or effects correction by adding or subtracting a predetermined amount to or from a present crank angle average period.
The ignition correcting unit of the ignition controller for an internal combustion engine in accordance with the invention corrects again one of the once-corrected ignition energization start timing and ignition timing at the time of inputting of the crank angle signal prior to effecting that ignition control.
The ignition correcting unit of the ignition controller for an internal combustion engine in accordance with the invention synchronizes the corrected ignition energization start timing and ignition timing with a crank angle signal immediately close thereto.
These and other objects and advantages of this invention will become more fully apparent from the following detailed description taken with the accompanying drawings in which:
FIG. 1 is a system configuration diagram in accordance with first, second, and third embodiments of the invention;
FIG. 2 is a diagram of a cam sensor in accordance with the first, second, and third embodiments;
FIG. 3 is a diagram of a crank angle sensor in accordance with the first, second, and third embodiments;
FIG. 4 is a timing chart in accordance with the first, second, and third embodiments;
FIGS. 5A and 5B are diagrams illustrating fluctuations in the engine speed in accordance with the first, second, and third embodiments;
FIG. 6 is a basic flowchart in accordance with the first and second embodiments;
FIG. 7 is a flow chart in accordance with the first embodiment;
FIG. 8 is a flow chart in accordance with the first embodiment;
FIG. 9 is a flow chart in accordance with the second embodiment; and
FIG. 10 is a flow chart in accordance with the third embodiment.